Spinal muscular atrophy (SMA), a commonly fatal autosomal recessive disease, is caused by the degeneration of spinal anterior horn cells. It leads to symmetrical limb and trunk paralysis and muscular atrophy. SMA has been linked to the protein product of the Survival of Motor Neurons (SMN) gene. In greater than 98% of all SMA patients, SMN has been reported to be deleted or mutated. Although its function is unknown, the SMN protein is highly concentrated in novel nuclear structures, termed gems. SIP1 (SMN-interacting protein 1) forms a stable heteromeric complex with SMN and colocalizes with SMN in gems and in the cytoplasm. In SMA, the expression of both proteins is dramatically reduced in motor neurons. Additionally, SMN and SIP1 have been isolated from a 300 kDa protein complex that also contains spliceosomal snRNP proteins. In particular, the SMN-SIP1 complex associates with the spliceosomal snRNAs U1 and U5. Antibodies against the SMN-SIP1 complex interfere with the assembly and nuclear importation of spliceosomal complexes. Thus, it is thought that the SMN-SIP1 complex mediates the formation of spliceosomal snRNPs. However, the exact role of SIP1 in rRNA processing has yet to be determined.
This antibody is routinely tested by western blot analysis. Other applications were tested at BD Biosciences Pharmingen during antibody development only or reported in the literature.